While the phrase "intitle:index of" might look like a random string of technical jargon, it is actually one of the most powerful "Google Dorks" in existence. For researchers, it’s a way to find open directories; for website owners, it’s often a sign of a massive security oversight.

"Intitle:index of private" is a specific search query known as a Google Dork

Using this technique can expose highly sensitive information that organizations or individuals accidentally left open: Osint Search-Techniques | PDF | File Format - Scribd

location /private 
    autoindex off;
    # Alternative: Force a 403 error
    return 403;